“It’s perfect! I can prove there hasn’t been any murder whatsoever.”
The detective looked at the bleeding, perforated body.
“How do you figure that,” he muttered with dread.
“Well, you know: There are what, a thousand people, two thousand, at this convention?”
“Yep,” the detective said, covering the body under white linen.
“And this guy, he’s part of the convention, an attendant?”
“Yes,” the detective grumbled.
“So, if we take the odds, that is, one out of two thousand, the chances are pretty slim.”
“Chances? What chances.”
“The chances that any member of the convention has been murdered.”
The detective resisted the urge to draw upon the idiot.
“But we can see,” he reasoned, “that is, we observe that there has been a murder.”
“Precisely,” came the reply. “We know that there has been a murder, only one, out of two thousand. Well, those odds are pretty slim, almost zero. Therefore, knowing that someone has been murdered, we can reason that, statistically, taking this man as a sample out of the two thousand, he very likely has not been murdered.”
The detective considered how the mathematics would work out, all things being equal, if there were to be another murder.
(A poor attempt at a joke of Douglass Adams where he “proves” that the universe is unpopulated.)